A magnetoresistive sensor is commonly applied to an electronic compass for finely sensing the magnetic field change of the earth. Such a type of magnetoresistive sensor generally need be equipped with a conductor, e.g. a barber-pole conductor, which facilitates the direction change of current flow inside the magnetoresistive material and thereby increases the sensitivity of the magnetoresistive sensor. FIG. 1 shows a schematic cross-sectional view of a conventional magnetoresistive sensor. As illustrated in FIG. 1, the conventional magnetoresistive sensor 100 primarily includes an insulating substrate 102, a magnetoresistive structure 104, and a layer of conductor lines 106. The magnetoresistive structure 104 includes a magnetoresistive layer 112 and a hard mask layer 114. The hard mask layer 114 is disposed on the magnetoresistive layer 112. The magnetoresistive structure 104 is disposed on the insulating substrate 102. After forming a metal layer (not shown) on the magnetoresistive structure 104, the layer of conductor lines 106 is formed by etching the metal layer.
FIG. 2 shows a schematic top view of the magnetoresistive sensor as shown in FIG. 1. As seen from FIG. 2, a lengthwise extending direction of the conductor lines 106 is intersected a lengthwise extending direction of the magnetoresistive structure 104 with an angle of about 45 degrees. The conductor lines 106 are electrically connected with the magnetoresistive structure 104 to form barber-pole conductors. During a conventional process of fabricating such a magnetoresistive sensor 100, since the magnetoresistive structure 104 is firstly formed on the insulating substrate 102 and then the conductor lines 106 are formed on the magnetoresistive structure 104, the hard mask layer 114 is necessarily used to resist from etching occurring while defining the conductor lines 106, so that the overall thickness becomes undesirably large, resulting in degraded sensitivity of the magnetoresistive sensor 100.